Reevaluating the Activity of ZIF‐8 Based FeNCs for Electrochemical Ammonia Production

The electrochemical reduction of N2 in aqueous media and ambient conditions would present a great advancement in the defossilization of the fertilizer and energy sector, if the obstacles to this technology were not as significant as they are at present. Some recent reports have raised doubts about whether the electrochemical nitrogen reduction reaction (eNRR) is even possible in aqueous media. Herein, a type of metal‐organic framework (MOF)‐derived Fe and Zn single atom catalyst for the eNRR is revisited, which has been reported more than once in recent literature to be active for eNRR in aqueous media. Electrochemical measurements reported here show the inactivity of the investigated iron‐based catalysts for the eNRR in neutral aqueous media when contaminations are excluded. In stark contrast, the reduction of NOx contamination to ammonia is shown to be a possible reason for false positive results. The reduction of nitrate to ammonia (NO3‐RR) is itself an emerging field of research that investigates the conversion of nitrate from wastewater to ammonia. For the NO3‐RR, the MOF‐derived catalysts show good activity and selectivity, which depends on the iron site density in the catalyst. An ammonia yield of 19.1 mg h−1 mgcat−1 at −1.0 V versus RHE and a maximum faradaic efficiency (FE) of 100% at −0.9 V versus RHE is achieved.